In addition to being available in many displacements, the modern internal combustion engine is capable of being provided by the manufacturer in many variations to suit the preferences of the driver and to meet certain anticipated driving demands. The vehicle buyer can choose from an increasingly broad array of vehicle options, many of which including drive units or power takeoffs that are directly attached to the engine itself. In addition, the manufacturer may elect to include or not include one or more units based on vehicle configuration.
For example, the engine may be equipped with Rear End Accessory Drive (READ) unit driven by a camshaft. It is possible to have more than one READ unit in the event that the engine has more than one camshaft. These units are selected from coolant, fuel, and vacuum pumps which provide complex component and system assembly packages. When the cylinder head assembly is equipped with one or more such units, components of the assembly are machined and assembled as required to provide for proper and full functioning of the accessory unit.
In the event that one or more units is not included in the engine assembly, a block off plate is fitted in place of the portion of the accessory unit that attaches to the cylinder head assembly. While appearing to be a practical solution to the absence of an accessory unit, the use of the block off plate has certain known challenges that include increased component costs, increased assembly costs, increased leak paths, increased overall engine weight, and the need for additional packaging space.
More particularly, when a block off plate is used in place of the accessory unit, cylinder head and cam cover sealing becomes quite complex due to having to seal the pump area at the rear of the cylinder head. Known assembly requires updates to the cylinder head, the cam cover, additional sealing cam caps, press-in place (PIP) seals, room temperature vulcanizing (such as RTV sealant) and anaerobic sealant to seal the joint(s) properly. Unique cylinder head assemblies and/or cam cover(s) assemblies are required to contain complexity driving additional investment and processing.
Thus a new approach to sealing an internal combustion engine in the event that an accessory unit is elected against is needed to address the problems associated with known arrangements.